Plastic injection apparatus and method



May 31, 1949. w. P. couslNo 2,471,814

' PLASTIC INJECTION APPARATUS AND METHOD Filed May 10, 1946 5 Sheets-Sheet 1 May 31,' 1949. w. P. couslNo 2,471,814

PLASTIC INJECTION APPARATUS AND METHOD Filed May 1o, 1946 3 Sheets-sheet 2 l IN VEN TOR.

M/alfef' Jansz-n0.

May 31, 1949. w. P. couslNo PLASTIC INJECTION APPARATUS AND METHOD 5 Sheets-Sheet 3 Filed May 10, 1946 NVENTOR. Waffe/v fazzfz'fza.

Patented May 3.1,y 1949 UNITED STATES TENT OFFICE PLASTIC INJECTION APPARATUS AND METHOD Walter P. Cousino, Detroit, Mich., assignor to Chrysler Corporation, Highland Park, Mich., a

corporation of Delaware 14 Claims.

This invention relates to an improved apparatus for and method of injection molding and is an improvement upon the injection molding apparatus and methods disclosed in my co-pending applications Serial Nos. 471,693, now Patent No. 2,402,8U, 521,197, and 556,119, filed January 8, 1943, February 5, 1944, and September 28, 1944, respectively.

More particularly, the invention relates to an improved nozzle structure which may be advantageously used in injection molding Iof vplastic compounds of 1both thermoplastic and heat curable types which shrink during conversion from a relatively flovvable to a solid state.

The molding apparatus embodying the invention comprises generally a relatively shiftable injecting unit vand mold having a nozzle and mold inlet, respectively, Which are brought into and out of mold-lling relation by such relative shifting movement. with mechanism for releasably, yieldably, relatively urging the mold and injecting unit together in order to retain Ithe nozzle of the injecting unit and inlet of the mold in mold-filling relation. This mechanism is adapted to accommodate relatively slight separatory movement of the injecting unit and mold under the action of the pressure on the contents of the mold when the mold is filled. Such relative separatory movement is relied upon to actuate certain control mechanism, with which the injecting unit is provided, for the purpose of simultaneously discontinuing operation of the main plastic displacing means of the injecting unit and operating valve means on the Iino-stream side of the nozzle for cutting off the iiow of compound `from the displacing means to the nozzle and reverse flow of compound from the mold through the nozzle.

One of the main objects of the invention is to provide in injection molding apparatus of this character an improved nozzle structure which maintains pressure upon the contents of a filled mold throughout that period following the moldlling operation during which shrinkage occurs yas the contents of the mold undergo setting action.

Another object of the invention is to provide an injection nozzle of this character which supplements the contents of the mold during shrinking'of the compound therein as the com-pound sets in order to compensate vfor such shrinkage while the main compound displacing means of the injecting unit is inoperative.

A further object of the invention is to provide an extensible and contractable nozzle in inject- The apparatus is provided ing apparatus of this character having a part which remains in pressure communicative relationship with the mold inlet after the injecting -unit and mold have been urged apart by the pressure of the compound in a filled mold.

Another object of the invention is to provide in a nozzle of this kind, a contractable chamber from which compound is displaced from the nozzle into the mold under the force by which the injecting unit and mold `are urged together after operation of the main compound displacing mechanism has ceased, following a mold-filling operation.

A still further object of the invention is to Drovide improved control mechanism for injecting apparatus of this character which simultaneously discontinues compound discharging operation 0I" the main compound displacing means and closes the passage in the injecting apparatus leading to the nozzle and thereafter maintains the yforce by which the injecting unit and mold are urged together for a predetermined period in order to utilize this force for the purpose 'of retaining the compound in the nozzle chamber under pressure vand holding the nozzle in pressure communicating relation to the mold inlet during at least initial setting of the compound in the mold.

A still further object of the invention is to provide improved control mechanism of this kind which will accommodate the approaching movement oi the injecting unit and mold which contracts the nozzle chamber, without `bringing the compound displacing mechanism and valve control means into actuation.

Another object of the invention is to provide in an injecting unit control system mechanism which will cause the compound displacing apparatus and valve opening device to function during only alternate approaching movements of the relative shiftable mold and injecting unit.

An illustrative embodiment of the invention is shown in the accompanying drawings, in which Fig. l is a fragmentary, side elevational view of injecting apparatus embodying the invention.

Fig. 2 is a vertical sectional view taken on line Z-'Z of Fig. 1.

Fig. 3 is a fragmentary, plan View of the injecting apparatus shown in Figs. 1 and 2, as viewed from line `3-3 of Fig. 1.

Fig. 4 is an enlarged, fragmentary vertical section-a1 View on the line llof Fig. 2 showing details of construction of the nozzle of the injecting apparatus.

Fig. 5 is a sectional View similar to Fig. 4 but illustrating a nozzle structure embodying a modied form of the invention.

Fig. 6 is a sectional view similar to Figs. 4 and 5 but showing 4a nozzle structure which embodies a still further embodiment of the invention.

Fig. 7 is `a horizontal sectional view taken on line 'I--l of Fig. 2.

In the forms of the invention shown in the drawings, the injecting apparatus comprises a tubular body portion, shown in Fig. 2, generally designated by the numeral Ill, and having an upper section I l, an intermediate section IZ, and a heating chamber I3 to which is attached a valve body I3 having a valve element It provided with an operating lever I5'. A nozzle body It having a discharge nozzle element I5 located at its extreme end is mounted on the lower end of the valve body I3.

The intermediate section l2 is provided with a bore IB which is axially aligned with the passage Il in the heating chamber as well as with the entrance passage I8 of the nozzle. A conveyor-like screw 2U extends through the bore i6 and is provided with a thread ZI which relatively closely iits the wall of the bore I6 and which extends vthrough the interior of the upper section i I to a location adjacent the valve body I3. Provided on respectively opposite sides of the bore I6 are chambers 22 and 23 which are formed in part by slots 24 and 25, respectively, provided through lthe wall structure of the intermediate section I2, and in part by recesses 26 and 2l of caps 23 and 2193, respectively, which are mounted on the sides of the intermediate section I2 in alignment with the slots 24 and 25 thereof.

Rotatably mounted in each chamber 22 and 23 is a gear-like element 3u and 3l, respectively, having teeth meshed with. the thread 2l of the screw ZI] in a worm and gear relationship. Each of the gears 3,5 and 3l have bosses .'53 extending from their opposite sides which are journalled in apertures 34 formed partially in the wall structure of the intermediate section I2 and partly in the caps 28 and 2Q. The bosses 33 are rotatably received within bearing elements 35 disposed in .the apertures 34 which are held against axial displacement from the apertures 35 by plugs 36 and 31. The plug 36 comprises a metal disc having its peripheral portion seated in a groove 38 formed in the wall structure of the intermediate section lI2 and associated cap. The plug 3? comprises a metal sleeve having a radially extending flange `3,9 seated in a groove 40 similar to the groove 38. The plug 3'! is provided with a central threaded aperture in which a threaded plug lil is disposed. The plug il engages the extremity of one boss 33 of each gear and serves to hold the opposite extremity o f the other boss 33 thereof against an abutment 42 provided on the inner side of the plug 35.

The gears 3E! and 3l serve as rotatable dams and the teeth thereof extend into the groove of the thread 2| of the screw 2!) to positively oppose turning of material operated upon by the thread of the screw with the latter. In this manner, a pressure is positively built up upon the material within the bore I5 of the intermediate section I 2, as well as upon the material contained in the passage I'I of the heating member I3. The teeth of the gears 30 and 3l are meshed with the thread 2l of the screw 20 at a location spaced from the inlet end A3 of the intermediate section I2, There is at least one complete full turn of the thread of the screw 20 which is in close iitting relationship with respect to the wan of the tore i6 between the inlet end of the bore I5 and the location at which the slots 24 and 25 communicate therewith. With this construction any material operated upon by the screw which is displaced from the bore I6, by reason of its being carried between the teeth of the gears 30 and 3|, is returned to the bore at a location at which the material is at least initially compressed by the thread of the screw. Therefore, the moldable material which thus flows through the chambers 22 and 23 is not removed from a zone of high pressure to a zone of atmospheric pressure and accordingly compressive work which has been done on this material is not lost.

The screw 2i) has a shank ll on its upper extremity of substantially square cross section which is received in a correspondingly shaped socket l5 of a spindle 45. A pin 'i extends through openings in the wall of the socket 45 and a registering opening 58 in the shank 44 for holding the screw against displacement from the spindle. The injecting unit is provided with mechanism for driving the screw which includes a motor 53 having a shaft 543 provided with a worm 55 which is meshed with a worm gear 56 keyed to the spindle fit. The motor is supported by and the transmission gearing is disposed within a housing 51 spaced vertically from the intermediate section I2 of the injecting apparatus by the tubular structure, heretofore referred to as the upper section II of the injecting apparatus, which is preferably formed integral with the transmission housing. The spindle is rotatably supported by spaced rolling contact bearing units 58 and 5S mounted in the housing 57 and cover plate 6@ of the latter, respectively. A thrust bearing unit 5I disposed between the cover plate and a spacer 62 which bears upon one side of the worm gear 56, opposes axial movement of the latter in one direction and a thrust bearing unit I63 disposed between the bearing unit 53 and the other side of the gear opposes axial movement of the worm gear in the opposite direction.

When the injecting apparatus is used in moldlling operations it is preferably pivotally mounted on a support 'I3 for rocking :movement about an axis M into and out of mold-lling relationship with respect to a die or mold generally designated by the numeral 15. For the purpose of illustration, the mold is shown in the drawings to include separable parts T16 and 'il mounted on the support i3 and on a shiftable ram '53, re.- spectively.

The material to be injected may be heated while it is in the injecting apparatus in any suitable manner. An electric heating element i9 may be provided in the wall structure of the heating chamber I3 or the wall structure of the latter may be cored out to accommodate supply of any suitable heating medium. A gap 8l is preferably provided between the main portions of the adjacent ends of the intermediate section I2 and heating chamber I3 in order to reduce the transmission of heat from the latter to the material in the vicinity in which it is being initially placed under compression.

The discharge nozzle I5 comprises a tubular body part 82 in which is formed the entrance passage I8. A tubular discharge section 83 is axially slidably mounted in the passage I8 of the body portion 82 and provided with a central discharge passage 84 which is adapted to feed moldable material into the inlet `opening 85 of 5 the mold 'I5'. The inlet opening 85 has a bevelled seat with which a correspondingly bevelled end portion 8B provided on the outer extremity of the discharge section 8.3 of the nozzle is adapted to register. In order to prevent separation of the inner discharge section 83 of the nozzle from the body portion 82 thereof and to limit axial movement of the discharge section 82 with respect to the body portion, a recess al is provided in the side of the discharge section 83 for receiving a pin 88 mounted in the wall of the body portion 82. The upper and lower ends of the recess 81 abut opposite side portions of the pin 88 and thus establish the lower and upper limits of movement, respectively, of the discharge section relative to the body portion of the nozzle. When the injecting unit and mold are in the mold-lling relationship shown in Figs. 1 and 2, the nozzle is urged toward the mold as hereinafter more clearly set forth and the parts f the nozzle are held in contracted position by the force with which the nozzle is urged toward the mold. The parts of the nozzle remain in contracted position during the mold-filling operation and until the mold is completely filled.

When the mold is completely filled, further momentary displacement of compound from the pressure chamber of the injecting unit extends the nozzle to the position shown in Fig. 4. As hereinafter more clearly set forth, discharge rotation of the screw is discontinued and the valve I4 is closed when the nozzle is extended by the action of the pressure created by the screw immediately after the mold is completely filled., When the mold has thus been filled and discharge operation of the screw 2i? has been discontinued and the valve I4 has been closed, the force by which the injecting unit is urged, as hereinafter set forth, in a counterclockwise direction, as viewed in Fig. 1, about its pivotal axis It, retains the compound in the mold under pressure while it is being set either by a heat curing or cooling action. Inasmuch as many moldable compounds of the type capable of being injected by the improved apparatus, shrink upon solidifying, the 1 force by which the nozzle body 82 is urged downwardly, as viewed in Fig. 4, causes contraction of the discharge section 83 which displaces moldable material from the nozzle into the mold inlet so as to compensate for such shrinkage and to maintain the contents of the mold under uniform pressure during the solidifying stage.

In Figs. 5 and 6 are shown two modications of the nozzle structure illustrated in Fig. 4. In the form shown in Fig. 5 the nozzle body 82 is provided with a shoulder all which is adapted to engage the inner end of the shiitable section 83 of the nozzle when the nozzle is in its contracted condition. Engagement of the inner end of the shiftable discharge section 83 of the nozzle with the shoulder il@ forms a seal which serves to prevent the flow of material being discharged through the nozzle between the engaged sur faces of the body portion 82 and discharge section 83 of the nozzle.

In the form of the invention illustrated in Fig. 6 the body portion 82 of the nozzle is provided with a shoulder Sil against which the inner extremity of the shiitable discharge section 83 of the nozzle abuts, as in the form shown in Fig. 5. However, in this form of the invention there is provided between the body portion 82 of the nozzle and the shiftable discharge section 83 thereof a sleeve or collar 9| having an upper extremity 92 spaced from the shoulder 50. The

shiftable section 83 of the nozzle is provided with a head portion S3 which is disposed between the shoulder of the body portion of the nozzle and the upper extremity 92 of the sleeve 9i. When the nozzle is in contracted condition, the upper extremity of the shiftable section 83 thereof bears against the shoulder 95 to form a seal against admission of moldable material between the nozzle body and shiftable section, 'Ihe upper extremity 92 of the sleeve 9| abuts a shoulder 94 formed on the head part $13 of the shiftable section 83 to limit outward extension of the shiftable section B3 with respect to the body portion 82 of the nozzle. Engagement of the surfaces 92 and 91% occurs when the nozzle is in its maximum extended condition and serves to prevent the flow of moldable material beyond the location of these engaged surfaces.

rIhe injection molding apparatus which is provided with the improved nozzle for compensating for shrinkage which occurs during solidication of moldable material in a mold is provided with a control system which serves to accommodate displacement of a small charge of moldable material from the nozzle after the mold has been initially filled. This control apparatus is best shown in Figs. 1 and 2. It includes a cylinder 98 mounted on a support 93 in which is slidably disposed a piston 99. The piston 99 has a piston rod Idil which is pivotally attached at Iii! to the injecting unit on the right hand side of the pivotal axis "i4, as viewed in Fig. 1. Fluid pressure may be admitted to the lower end of the cylinder @ik by a conduit I2 in order to urge the piston at upwardly and thus rotate the injecting unit in a counter-clockwise direction about its pivotal axis it. Fluid pressure may be admitted to the upper end of the cylinder 93 through a conduit E63 in order to rotate the injecting unit in a clockwise direction about its pivot It. 'Ihe conduits It? and lili are connected with a valve, generally designated by the numeral ltd, which includes a housing structure E55 having a rotatable valve element IBS journalled therein. An operating lever Ill? is attached to the rotatable valve element I for rotating the latter to selectively admit uid under pressure to either of the conduits IIB? or |03. When the valve is in the position shown in Fig. l, fluid is supplied through the inlet pipe Hi8 to the passage lil@ of the valve element m5 and from the passage It to the conduit |92. conduit Hit is connected with atmosphere by an exhaust groove I Ill formed in the rotatable valve element IBG and through a conduit III which communicates with the groove I I t. When the valve element Iilii is rotated in a counterclockwise direction, as viewed in Fig. 1, the passage Iilfl of the rotatable valve element is brought into communication with the conduit H03 and fluid pressure is supplied to the upper end of the cylinder 93, while the groove IIE) is brought into communication with the conduit IBZ for the purpose of exhausting nuid pressure from beneath the piston 99. Movement of the nozzle of the injecting unit into and out of mold-filling relationship with respect to the mold may be effected by control of the valve IM.

The valve element Ill is normally urged toward Iits closed position by a spring H2 which is attached to the valve lever I5. The Valve I4 may be opened against the action of the spring I5 by a solenoid H3 which is mounted on the injecting unit and connected by a rod H4 with the valve lever l5.

The

' Aa roller The motor 153 yby vwhich the screw 120 iis driven iis yo'f 4a reversible driving type and is provided withfaterminal AH which isconnected byfa conduit |16 with one conductor |'l` of a power line. 'The Iother conductor ||8 of the power line is Jadapted to be connected with a terminal ||9 of the motor :through a switch `comprising a switch :element -in order to establish rotation of the imotorto drive the screw in a forward pressure- 'creating direction. The switch element |20 is normallyurged out of contact with a xed switch element |22, `connected with the terminal .H9 lof :the motor, by `a spring |23 and is adapted to be urged against the action of the spring |23 :into engagement with the contact |22 by a fsolenoid |24. When the solenoidl l-Zfi is deienergized, as :hereinafter Yset forth, the movable switch element |20 is urged in a counter-clockwise/.direction as .viewed in Fig. l until it engages yfafoontact `|255 which is connected by a conductor |26 through a switch, generally designated by :theinumera'l |27, with a conductor mit which is :connected with ythe reverse terminal |2| of the motor '53. lThe switch |27 is adapted to :maintain reverse `operation of the motor and accordingly reverse pressure-relieving driving of the scr-ew 2d throughout a predetermined portion 4of a .rotation of the screw. The switch mechanism |21 is substantially identical to that l:shawn :in fapplicants :copending application Serial No. 521,197 and it includes an operating lever |28 on `the free end of which is provided |29. This switch is associated with switch-actuating mechanism which is responsive `to rotation of the spindle it by which the screw 2U .is `drivingly rotated. The switch-operating ,mechanisrm shown in Fig. 8, comprises a rotor |30 whichconsists of an integral extension of the spindle Mi. The rotor I3@ is surrounded by a split-ring y|3.| comprising frictional material hav- .ing asplit metal band |32 on its outer periphery. .'Iihe :band |32 preferably comprises resilient :meta-l, such-as spring steel, and is conditioned to frictionally urge the f-rictional material itl against the periphery 0i' the rotor i3d. Mounted 4on the metal band |32 are arcuately spaced .brackets |33 and |34 having outwardly extending anges. The rotor |39 is disposed within a housing |35in which is shiftably .mounted a slide bar |36. The end portions of the slide bar .|36 extend outwardly of the housing |35 through slots |31 formed inthe wall of the housing. The upper .end of the bar It@ is adapted to engage the-roller .|29 of the switch lever |28 and to move the .latter to its switch-opening position when lthisbaris shifted upwardly, as viewed in Fig. 3.

Forward rotation of the screw 2|] and of the rotor |30 lis .in a clockwise direction, as viewed in Fig. `3. During this clockwise rotation of the ,rotor |30, which occurs while the material is `being discharged from the apparatus, .the vout- .wardly extending flange of the bracket |33 on the metal band |32 abuts the upper side of a 'lug |38, as viewed in Fig. 3, which extends leitwardly from the slide bar |36. Engagement of the 'bracket |33 with the lug |38 ,prevents fur- -ther rotation of the band |32 and frictional material `|3`| attached thereto in a clockwise direc- `tion with the rotor |30. The rotor |30 and screw 2G with which it is connected may thus continue to yrotate in a clockwise direction while the bracket y|38 of the split band |30 'holds the slide bar |35 in its downward limiting position, as viewedin Fig. 3, which is established by engagement of a stop |39 carried by the slide bar,

LU I' with `rthe housing 135, :as .illustrated in Fig. f3.

lThus, during and |following a discharge operation of .the machine, the contacts -(not shown) o'f the switch |21 are maintained closed.

The Yswitch |27 is provided with a terminal |69 which is connected by .the conductor |28 with vthe center terminal |2| of the motor l53. Another terminal Ml `on the switch |27 is connected by the conductor lit with the fiXed'switch Contact element |25 which is adapted to .be

`engaged. by the movable switch element I'|2ll ywhen the solenoid |24 is de-energized. Engagement of .the movable switch contact element |29 with the fixed switch element |25 completes a circuit, when the switch |27 is closed as1above described, through the motor 53 which drives the motor in a reverse direction. 'This reverse ydriv ing circuit is established by current supplied from the conductor ||l` of the power .line to the terminal H5 ofthe motor 53, through the motor and from the terminal |2| of the motor through the switch Kel, conductor |26, engaged switch elements |23 Vand |25, and through a conductor M2 leading from the movable switch contact element i2@ to the conductor i3 of lthe lpower line.

A reverse operation of the motor 53 rotates the rotor liii in fa counterclockwise direction, as viewed in Fig. 3, and the split band |32 and frictional material |3| are carried with it in a counterclockwise direction, bringing ythe flange i3d into engagement with the lower side of the lug |38. Further counter-clockwise rotation of the split band |252 and bracket i3d shifts vthe slide bar |36 upwardly, as viewed in Fig. 3, Iuntil a stop M3 mounted on the slide bar engages the -wall of the housing |135 to establish the ilimiting upward position of the slide bar. As the slide bar |35 is moved to its extreme upward limiting position, as viewed in Fig. 3its 'external end portion engages the roller |29 of the Switch lever |23 and rotates the latter to its off position, thereby breaking the circuit to the terminais |2| and H5 of the motor 53. When the circuit leading to the motor terminals |2| and lili is thus broken, reverse drive operation `of the motor and screw 2li is discontinued. The duration of the reverse drive operation maybe predetermined by suitably locating the brackets |33 and i3d in angularly spaced relationshipwith respect to each other. During initial driving of the apparatus in a .forward discharging direction, the bracket |33 engages the left side "of 'the lug l'ddand returns the slide bar |36 to its lowermost position, illustrated in Fig. 3, causing fthe switch iil to be closed in prepa-ration for the next reverse driving operation which doesnot immediately take place inasmuch as the switch v'contacts |22@ and |25 are separated during the forward drive of the motor 53 and screw l21|, as

`hereinafter more clearly set forth.

The control apparatus includes means for automatically starting the motor in its forward driving operation when the nozzle i5 of the in- `iecting unit is brought into mold-filling .relation- .ship with respect to the inlet of the mold 15 at the Vcommencement of a mold-filling operation. This control apparatus also functions to discontinue the forward drive ofthe Imotor when the mold is ylled and to initiate a reverse drive As previously `set forth, upon completion of filling of the mold, the nozzle I5 is extended in response to `pressure of thematerial in the moldfand this extension of ythenozzle is 'accommodated by 4pivotal movement Aof the infj ecting apparatus in a clockwise direction, as viewed in Fig. 1, about its pivotal axis 14. This clockwise pivotal movement of the injecting unit occurs against the fluid pressure on the underside oi the piston and therefore the injecting unit is urged by the piston 90 in a clockwise direction, which action tends to contract the nozzle I5. Such contraction of the nozzle takes place as the material in the mold shrinks dur-- ing setting, thus compensating for shrinkage and maintaining pressure on the contents in the mold in the manner previously set forth. During such contraction of the nozzle the apparatus is moved towards its mold-lling relationship with respect to the mold, and provision is made the control apparatus for preventing unintended initiation of the mold-filling cycle during this relan tive approaching movement of the injecting unit and mold7 which is relied upon to contract the nozzle and displace mcldable compound from within it.

The foregoing functions are accomplished by the control system which. in addition to the above described apparatus, includes a switch, generally designated by the numeral |44, having iixed contacts |45 and |40 and a movable contact element |41 The movable contact element |41 is engageable by the operating lever |01 of the valve mechanism |04, and is adapted to be moved thereby into closed position with respect to the contacts |45 and |135, when fluid pressure is admitted by the valve E04 to the lower end of the cylinder 00. The iixed contact |40 is connected by a conductor M0 with one conductor |49 of a control power line. The other fixed contact |45 of the switch |44 is connected by a conductor l 50 with a Solenoid coil Uil. Shiftably mounted within the solenoid coil |5| is an armature |52 which is normally yieldably urged leftwardly, as viewed in Fig. 1, by a spring |53. the left end oi" the armature |52 is a dog |53 which is adapted to cooperate with a ratchet wheel |54 journalled on a bracket |55 which is carried by the injecting unit* The coil |5| and spring |53 are also mounted on the bracket |55. The ratchet wheel H54 has a hexagonal-shaped block of electrical insulating material |50 co-axially mounted upon it and fixed to it. Alternate sides of the hexagonal block |50 are provided with contact elements |51. all of which `are connected with a conductor |53 which is in turn electrically ccnnected with the conductor 50. A brush-like contact element U50 mounted on the bracket |55 is electrically connected by a conductor |0| with a switch contact element |52 of a switch, generally designated by the numeral |63. The switch |63 a movable contact element |04 which is mounted on and adapted to move with the injecting unit. The switch element |0| is mounted on the mold structure by a resiliently yieldable strip |65.

In order to complete a circuit through the coil |5| only when the mold and injecting unit are in a predetermined close relationship with respect to each other, such as is produced by the relative approaching movement of the injecting unit and mold whichv occurs during contraction of the nozzle. switch, generally designated by the numeral |05, is provided which has a movable contact element |61 mounted on the injecting unit and a relatively xed contact element |00 mounted on the mold. The contact element |61 is electrically connected by a conductor |09 with the other terminal of the coil |5l. `The switch contact element |00 is electrically connected by a conductor PVOtaHy mounted on trol power line.

|10 with the other conductor |1| of the control power line Movable switch contact element |64 of the switch 03 is connected by a conductor |12 with a movable switch element |13 of a delayed action relay, generally designated by the numeral |14. A iixed contact element `|15` of the switch of the delayed action relay |14 is electrically connected by a conductor i 1li with one terminal of the solenoid |24 by which the forward and reverse drive establishing switch, previously described, is operated. The other terminal of the solenoid |24 is connected by a conductor |11 with the conductor lli of the control power line. The delayed action relay 1li includes a spring |18 which normally urges the movable element |13 to its open position. This delayed action relay also includes a solenoid coil |19 having one terminal connected by a conductor to the conductor |11 which leads to the conductor |1| of the con- The other terminal of the solenoid E10 of the delayed action relay is connected by a conductor |8| with the movable switch element iii@ of the switch |03.

The solenoid i3 which operates the valve ||4" of the injecting apparatus has a terminal |82 electrically connected by a conductor |83 with the conductor i'ii and it has another terminal |84 connected by a conductor |05 with the conduc# tor |11.

In operation of the improved injection moldapparatus and its control system, the following sequence of steps and operations occur. As shown in Fig. l, the apparatus and control system are in condition to drive the structure 20 in its forward discharge direction in order to ll the cavity ci the mold with moldable material the valve iii is opened to accommodate the discharge of such moldable material. .testing unit had thus been previously moved to the position shown in Fig. l by operation of the control lever itl of the valve mechanism |04 which admitted fluid to the lower end of the cyl der 08 As the lever |01 was moved to the position shown in Fig. l, it closed the switch |44 and as the injecting unit was rotated to mold filling relationship with respect to the mold by the action of the piston 99, the switch |66 wasclosed. This established a circuit from the conductor |49 of the power line through the coil 5l to the conductor il! of the power line7 thus energizing the coil itil and consequently moving the armature |52 rightwardly against the action of the spring |53. This action caused the dog |53 to index the ratchet |54 a distance corresponding to one tooth of the ratchet, thereby bringing the contact element |51 on the hexagonal block |50 into engagement with the brush contact element |60. This indexingI of the ratchet occurred during the relative approaching movement of the injecting unit and mold and during the same approaching movement the switch it was also closed. Engagement of a contact i 51 on the hexagonal block with the brush contact element |00 and closing of the switch |63 supplied current from The in- 1'1 the fixed `switch element |122, thereby establishing the forward drive of the motor 53 and screw 26. All of the foregoing control operations, as previously stated', took placey as the injecting unit and mold: came into mold-filling relation and duringfthisrelative approachingmovement of the injecting unit and mold a circuit was also completed through the solenoid H3 which controls the valve i4 of the injecting unit, this latter circuit being completedA by reason of the closed conditionsof the switches |45, ratchet switch having contact elements |65 and |51, switch |63 and theswitch of the delayed action relay including contacts |13 and |15. e

From the foregoing description of the manner in which the control apparatus `was placed in the condition shown' in Fig. 1, it will be seen that coincidental with relative shifting of the injecting apparatus and mold into mold-filling relationship, the' valve I4' is opened and the motor 53 is conditioned tof drive the screw 26 in its forward discharging direction. The valve M remains open and the motor 53` continues to drive the screw 2B until the mold is filled. Upon completionof filling of the mold the back pressure applied by the discharged moldable material urges the injecting unit in a counterclockwise direction about its pivot'TlI and against the action of the piston 99, thereby accommodating extension of the extensible nozzle I5. This relative pivotal movement of the injecting unit and mold causes both switches |63 and |66 to open. When the switch |63 is opened, thev coil |19 of the delayed action relay I1| is cie-energized and the spring |18 of this relay separates the switch Contact elements |13 and |15. Thus, the supply of current to both the valve control coil H3 and the reversing switch control coil |24 is discontinued. The spring ||2 shifts the valve lll' to its closed position and the spring |23 of the forward and reverse drive control switch moves the movable contactl |20# into engagement with the fixed contact |25. Since, as above described, the switch |21/ is closed following forward drive operation of the screw' 20, the motor 53 is reversed for a predetermined period of reverse driving operation. This reverse driving of the screw 26 by the motor 53 relieves the pressure upon the molda'ble compound in the injecting apparatus on the upstream side of the valve I4 thereof. Relieving of the pressure on the moldable material `at this location in the apparatus prevents unintended setting of. the compound in the apparatus, as clearly set forth in applicants copending application Serial No. 521,197.

After the motor has driven the screw in its reverse pressure-relieving direction for a predetermined interval established by the control switch |21 and its previously described operating mechanism, operation of the motor is discontinued and the content of the mold is solidied either by heating if the imoldable material is of a thermosetting nature, or by Icooling if it is thermoplastic. During this solidification of the mold content, the fluid pressure on the under side of the piston` 99 continues to urge the injecting unit in a counterclockwise direction about its pivot 14, thus tending to contract the extensible nozzle I5, Iwhich action maintains the contents of the nrold under pressure. Any shrinkage of the material in the mold which occurs during its solidication or setting is compensated for by contraction of the nozzle and displacement of compound from within it. As the nozzle contracts, the injecting unitapproaches the mold and the switches F63 and |66 are'again closed. 1t is not intended that circuits be re-established through the coils ||3 of the discharge valve operating. mechanism and |24 of the' forward and reverse control switch for opening of the valve I4" and further operation of the screw is not desired at this stage. The control mechanism guards against this occurrence by breaking the circuit at the ratchet control unit. When the switch |66 is opened in response to pressure of thel contents of the mold following completion of a amold-lling operation, the solenoid |5| of the ratchet mechanism is de-energized and the spring |53 shifts the armature |52 leftwardly, as viewed in Fig. 1, to position the dog for performing another indexing operation.

The moment contact is re-established during contractionof the nozzle between the contact elements |61 and |68 of the switch |66, current momentarily ows through the coil |5| and shifts the armature |52 leftwardly, thus indexing the hexagonal block |58 one step which brings the brush contact |66' out of'en'gagement with the contact member |51 and into engagement with oney of the sides of the hexagonal insulating block |56 which is disposed betweentwo successive contact elementsI |51. Duri-ng that interval of time thecoi-l |5 If isexcited for the purpose of indexing the ratchet mechanism', current is also supplied tov the coil |19 of the delayed action relay, but since the delayed action relay is predetermined inconstruction to require a greater length of time to close the switch of the delayed action relay than that required to index the ratchet mechanism one step', the circuit is interrupted between the brush element |66 and one of the contact elements |59 of the ratchet mechanism before the contacts |13- and |15 of the delayed action relay are closed. Thus the latter contacts are never closedv while the brush element |65 is not engaged with one of the contact elements |50 of the ratchet mechanism and, accordingly, the control system permits approaching movenient' of the injecting unit and mold during contraction of the nozzle I5 without bringing the motor 53 into operation and without opening the valve I4'. The control system therefore causes operation of the motor 53- in a forward driving direction and produces opening of the valve M' during only every alternate -relative approaching movement of the mold and injecting unit. The control system however assures discontinuation of the forward discharge driving operation of the motor 53 and closing of the Valve I4 each time the mold andv injecting unit undergo relative separatory movements.

When the material in the -mold has been solidi-fled to a desired extent, the operating lever |61 isrotated in a counterclockwise direction, as viewed in Fig. 1, to supply ud pressure to the upper end of the cylinder 9B thus rotating the injecting unit in a clockwise direction about its pivot 11|.y The switch |44 is opened as a result of the counter-clockwise rotation of the lever I 61 and supply of vcurrent to the coil |57! of the ratchet mechanism is consequently discontinued, permitting the spring |53 to urge the armature |524 leftwardly in order to condition the dog |53 to perform another indexing operation upon the ratchet wheel |54 yand hexagonal block |56 for the purpose of re-establishing engagement of the brush contact element |66 with one of the contact `elements on the insulating block |56 to pre-set the: control system for another cycle..

In the event the relative approaching movement of the injecting unit and mold., which occurs during contraction of the nozzle following lling of the mold, is insulicient to engage the contacts of the switches 53 and Hit, no precaution is required to prevent unintended opening; oi the valve I4 and energizing of the motor 5S but in this event, the ratchet mechanism is not advanced to bring the brush contact itil into engagement with a blank side of the hexagonal block l. Thus' when the switch IM is subsequently closed at the beginning of thel next molding cycle, the ratchet mechanism will be advanced one step thereby breaking the circuit between the brush contact |60 and one of the contact elements itil of the hexagonal block l. rlllis condition can be corrected by opening and closing the switch Mill' without moving the valve handle lill suiiiciently to effectively change the setting oi the hydraulic control valve lllli.

I claim:

1. Apparatus for 'injecting moldable material into a mold having an inlet including an injecting unit provided with a discharge passage and means for displacing material therethrough, a valve adapted to close said passage, a discharge nozzle having telescoping relatively shiftable nozzle secm tions, one of said sections being carried by said injecting unit and yieldably held in spaced relation to said mold by the other nozzle section when the mold is initially lled, said second mentioned nozzle section being registerable with said mold inlet and movable outwardly with respect to said Erst mentioned nozzle section by the pressure of the material in said nozzle when said mold is filled for yieldably spacing said pret-mentioned nozzle section from said mold, means relatively shiftably mountingl said injecting unit and mold for bringing; said nozzle into and out of moldlling relationship with respect to said mold inlet, mechanism for relatively urging said injecting unit and mold toward their mold-filling relationship and shifting said second mentioned nozzle section inwardly with respect to said iirst mentioned nozzle section for maintaining pressure upon the contents of said mold and displacing material from said nozzle into said mold to compensate for shrinkage of the material therein when said valve is closed.

2. Apparatus for injecting moldable material into a mold having an inlet including an injecting unit provided with a discharge passage and means for displacing material therethrough, a discharge nozzle having a body portion carried by said injecting unit and a relatively extensible and retractable section registerable with said mold inlet and yieldably holding said injecting apparatus and nozzle body portion in spaced relation. to said mold during mold--lling operations, said nozzle section being movable outwardly relative to said nozzle body portion by the pressure of the material in said nozzle when said mold is filled, means for relatively urging nozzle and mold toward each other, said nozzle section being movable toward said body portion of said nozzle by the force under which said nozzle and mold are urged toward each other for displacing ma terial from said nozzle into said mold to compensate 'for shrinkage of the material therein following a mOld-iilling operation.

3. In combination, a mold having an inlet opening and apparatus for injecting a moldable material into said inlet opening including an injecting unit comprising a relatively extensible and contractable nozzle having telescoping body and discharge portions, said discharge portion of said nozzle having a discharge passage communicating with said inlet opening, means in said injecting unit for discharging said material through said passage, mechanism for driving said means, said mold and injecting unit being relatively movable to accommodate extension of said discharge portion of said nozzle relative to said body portion of said nozzle in response to pressure of the material in said nozzle upon complete filling of said mold, means for discontinuing operation of said driving mechanism after said mold has been filled, and means for relatively moving said injecting unit and mold toward each other for contracting said nozzle to displace material therefrom into said mold during shrinkage of the material in the mold following filling thereof.

e. In combination, a mold having an inlet opening and apparatus for injecting a moldable material into said inlet opening including an injecting unit comprising a relatively extensible and contracte-ble nozzle having telscoping body and discharge portions, said discharge portion of said nozzle having a discharge passage communicating with. said inlet opening, means in said injecting unit for discharging said material through said passage, mechanism for driving said means, said mold and injecting unit being relatively movable to accommodate extension of said discharge portion of said nozzle in response to pressure of the material in said nozzle upon complete filling of said mold, a control system for said driving mechanism including means actuated in response to said relative movement of said injecting unit and mold for discontinuing operation of said driving mechanism, and means for relatively moving said injecting unit and mold toward each other for contracting said nozzle to displace Inaterial therefrom into said mold during shrinkage of the material in the mold following lling thereof.

5. In combination, a mold having an inlet opening and apparatus for injecting a moldable material into said inlet opening including an injecting unit having a discharge passage and comprising a relatively extensible and contractable nozzle communicating with said passage, said nozzle having a body portion carried by said injecting unit and a relatively shiftable telescoping dischargeportion provided with an outlet communicating with the inlet opening of said mold, a valve member in said discharge passage of said injecting unit, means in said injecting unit for discharging material through said passage and nozzle, mechanism for driving said means, said mold and injecting unit being relatively movable to accommodate extension of said. discharge portion oi said nozzle in response to pressure oi the material in said nozzle upon complete iilling of said mola, a control system including means for simultaneously closing said valve and discontinuing operation of said driving mechanism upon complete filling oi said mold, and means for relatively moving said injecting unit and mold toward each other for contracting said nozzle therebetween and displacing material from said nozzle into said mold to compensate for shrinkage oi the material in the mold following completion of lling thereof.

6. 'in combination, a mold having an inlet opening and apparatus for injecting a moldable material into said inlet opening including an injecting unit having a discharge passage and comprising a relatively extensible and contractable nozzle communicating with said passage, said nozzle having a body portion carried by said injecting unit and a relatively shiftable telescoping discharge portion provided with an outlet communicating with the inlet opening of said mold, avalve member in said discharge passage of said injecting unit, means in said injecting unit for discharging material through said passage and nozzle, mechanism for driving said means, said mold and injecting unit being relatively movable to accommodate extension of said discharge portion of said nozzle in response to pressure of the material in said nozzle upon complete lling of said mold, a control system including means actuated in response' to said relative movement of said injecting unit and mold for closing said valve and discontinuing operation of said driving mechanism upon complete filling of said mold, and means for relatively urging said injecting unit and mold toward each other for contracting said nozzle therebetween and displacing material from said nozzle into said mold to compensate for shrinkage of 1ythe material in the mold following completion of filling thereof.

7. A nozzle for conveying moldable material from an injecting unit to a mold inlet under pressure comprising an outer body portion securable to said injecting unit and having a passage therein, spaced opposed continuous circular internal shoulders extending inwardly of said passage, and a discharge element shiftably mounted in said passage having a head portion disposed between said shoulders and provided with continuous circular abutment surfaces, one engageable in sealing relationship with each of said shoulders, respectively, for obstructing the flow of moldable material between the adjacent surfaces of said body and discharge portions of said nozzle one of the engageable continuous circular surfaces on. said discharge element being located at the inlet end thereof.

8. A nozzle for conveying moldable material from an injecting unit to a mold inlet under pressure comprising an outer tubular body portion securable to said injecting unit and having an axial bore, a continuous circular shoulder in said body portion extending inwardly of said bore, and a tubular discharge element shiftably mounted in said bore in close-fitting relationship with respect to the wall of said bore and having an extremity shaped to lit said mold inlet and an opposite extremity engageable with said shoulder of said tubular body portion for limiting inward movement of said discharge element and holding plastic material from flowing between said body portion and discharge element, said shoulder being located inwardly of said body portion beyond the space therein occupied by said discharge element.

9. In combination, a mold having an inlet opening and apparatus for injecting a moldable material into inlet opening including an in jecting unit having a discharge passage and comprising a relatively extensible and contractable nozzle communicating with said passage, said nozzle having a body portion carried by said in jecting unit and a relatively shiftable telesccping discharge portion provided with outlet ccmmunicating with the inlet opening of said mold, a valve member in said discharge passage of said injecting unit, means in said injecting unit for discharging material through said passage and nozzle, mechanism for driving said means, means relatively shiftably mounting -said injecting unit and mold, said mold and injecting unit being relatively shiftable by pressure of the material in the mold when the latter is filled for accommodating extension of said discharge portion of said nozzle, a control system for said valve and driving mechanism including means for simultaneously opening said valve and actuating said driving mechanism and simultaneously closing said valve and discontinuing operation of said driving mechanism in response to relative approaching and separatory movements respectively of said injecting unit and mold, said control system including means for rendering it inoperative to open said valve and to actuate said driving mechanism in response to the rst relative approaching movement of said injecting unit and mold following a mold-filling operation, and means relatively urging said injecting unit and mold toward each other for contracting said nozzle therebetween and displacing material from said nozzle into said mold immediately after said valve is closed and operation of said driving mechanism is discontinued.

10. In combination, a mold having an inlet opening, an injecting unit for discharging moldable material into said mold, means relatively shiftably mounting said mold and injecting unit, means in said injecting unit for displacing moldable material therefrom into said mold, driving mechanism for said displacing means, said mold and injecting unit being relatively shiftable in a separatory direction by the back pressure of the material in said mold when said mold is lled, and a control system for said driving mechanism including means responsive to alternate approaching movements of said mold and injecting unit for actuating said driving mechanism and responsive to successive back pressure produced separatory movements of said mold and injecting unit for discontinuing operation of said driving mechanism.

l1. In combination, a mold having an inlet opening, an injecting unit for discharging moldable material into said mold having a discharge passage, a valve in said passage, valve operating mechanism means relatively shiftably mounting said mold and injecting unit, means in said injecting unit for displacing moldable material therefrom into said mold, driving mechanism for said displacing means, said mold and injecting unit being relatively shiftable in a separatory direction by the back pressure of the material in said mold when said mold is filled, and a control system for said driving and valve operating mechanisms including means responsive to alternate approaching movements of said mold and injecting unit for simultaneously actuating said driving mechanism and opening said valve and responsive to successive back pressure produced separatory movement of said mold and injecting unit for simultaneously discontinuing operation of said driving mechanism and closing said valve.

12. In combination, a mold having an inlet opening and apparatus for injecting a moldable material into said inlet opening including an injecting unit comprising a relatively extensible and contractable nozzle having telescoping body and discharge portions, said discharge portion of said nozzle having a discharge passage communieating with said inlet opening, means in said injecting unit for discharging Said material through said passage, mechanism for driving said means, said mold and injecting unit being relatively movable to accommodate extension of said discharge portion of said nozzle relative to said body portion of said nozzle in response to pressure of the material in said nozzle upon complete filling of said mold, a control system for said driving mechanism including means responsive to relative approaching and separatory movements of said mold and injecting unit for respectively actuating said driving mechanism and discontinuing operation of said driving mechanism after said mold is filled, and means relatively urging said injecting unit and mold toward each other for contracting said nozzle to displace material therefrom into said mold during shrinkage of the material in the mold following iilling thereof, said control system including means for rendering it ineffective to actuate said driving mechanism in responsive to the first relative approaching movement of said mold and injecting unit following a mold-lling operation.

13. In combination, a mold having an inlet opening and apparatus for injecting a moldable material into said inlet opening including an injecting unit having a discharge passage and comprising a relatively extensible and contractable nozzle communicating with said passage, said nozzle having a body portion carried by said injecting unit and relatively shiftable telescoping discharge portion provided with an outlet communicating with the inlet opening of said mold, a valve member in said discharge passage of said injecting unit, valve operating mechanism, means in said injecting unit for discharging material through said passage and nozzle, mechanism for driving said means, said mold and injecting unit being relatively movable to accommodate extension of said discharge portion of said nozzle in response to pressure of the material in said nozzle upon complete iilling of said mold, a control system for said driving and valve operating mechanisms including means responsive to relative approaching and separatory movements of said mold and injecting unit for respectively simultaneously opening said valve and actuating said driving mechanism and simultaneously closing said valve and discontinuing operation of said driving mechanism, means for relatively urging said injecting unit and mold toward each other for contracting said nozzle therebetween and displacing material from said nozzle into said mold to compensate for shrinkage of the material in the mold following completion of lling thereof, said control system including means for rendering it ineffective to actuate said driving mechanism and open said valve in response to the rst relative approaching movement of said mold and injecting unit following a mold-lling operation.

14. The method of molding plastic compound which comprises the steps of yieldably urging an extensible and contractable plastic discharge nozzle and the inlet of a mold in engaged moldlling relationship with said nozzle contracted by engagement with said mold inlet, injecting a mold-filling charge of said compound under pressure through a passage communicating with said nozzle and through a passage in said nozzle into said mold inlet from a source of said compound under pressure, continuing the application of pressure on said source after said mold is filled and until the back pressure causes extension of said nozzle, discontinuing the application of pressure on said source substantially immediately after a predetermined extension of said nozzle, solidifying the plastic compound in said mold, and maintaining the pressure upon and compensating for shrinkage of the compound in said mold during solidication thereof by contractive displacement of compound from the passage of said nozzle.

WALTER P. COUSINO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,367,204 Cousine Jan. 16, 1945 2,414,948 Hermanns Jan. 28, 1947 

